Flat cell battery with both terminals on one face

ABSTRACT

A FLAT CELL BATTERY HAS A WRAPPER CONSISTING OF TWO PIECES, EACH OF WHICH IS IN CONTACT WITH AN END ELECTRODE SO AS TO SERVE AS A BATTERY TERMINAL. ONE OF THESE WRAPPER PIECES OR A LAMINATED LAYER THEREOF IS WRAPPED AROUND THE EDGE OF THE BATTERY AND OVERLAYS THE OTHER WRAPPER PIECE TO PRODUCE A BATTERY HAVING BOTH TERMINALS ON ONE FACE. PREFERABLY THE WRAPPER PIECES ARE LMINATES OF METAL AND ELECTRICALLY CONDUCTIVE PLASTIC, WITH THE PLASTIC BEING IN CONTACT WITH THE END ELECTRODES AND AN EXTENSION OF THE METAL IN THE LAMINATE SERVING AS THE TERMINAL WHICH IS WRAPPED AROUND THE EDGE OF THE BATTERY, THE WRAPPED AROUND EXTENSION, WHICH MUST BE ELECTRICALLY INSULATED FROM THE WRAPPER PIECE OVER WHICH IT IS OVERLAID, MAY BE SECURED TO THE OTHER WRAPPER PIECE BY NONCONDUCTIVE ADHESIVES OR HEAT SEALS.   D R A W I N G

May 22, 1973 J. M. BILHORN ETAL 3,734,780

FLAT CELL BATTERY WITH BOTH TERMINALS ON ONE FACE Filed June 25, 1971 2Sheets-Sheet l WRAPPED ARDUND TERMiNAL WRAPPED AROUND TERNHNAL 5LAMINATED WRAPPER PIECE LAMmATED WRAPPER P\EC.E

30 100 LAMINATED wRAPPeR 30 I mace May 22, 1973 J, BILHQRN ETAL3,734,780

FLAT CELL BATTERY WITH BOTH TERMINALS ON ONE FACE Filed June 25, 1971 2Sheets-Sheet 2 WRAPPED AROUND TERMNAL' 5 I GO LAMmA'rew t 4 wRAPPeR 5mace T00 LANHNATED BWRAPPER PIECE 7O 3O WRAPPED AROUND 'TERNHNAL 5 105$0 T -r v E 106 @0 mace 1 LANHNATED y WRAPPER PECE 3,734,780 PatentedMay 22, 1973 3,734,780 FLAT CELL BATTERY WITH BOTH TERMINALS ON ONE FACEJohn M. Bilhorn, Edgerton, and Bernard C. Bergum and Kent V. Anderson,Madison, Wis., assignors to ESB Incorporated Filed June 25, 1971, Ser.No. 156,804 Int. Cl. H01m 21/00 US. Cl. 136--111 7 Claims ABSTRACT OFTHE DISCLOSURE A flat cell battery has a wrapper consisting of twopieces, each of which is in contact with an end electrode so as to serveas a battery terminal. One of these wrapper pieces or a laminated layerthereof is wrapped around the edge of the battery and overlays the otherwrapper piece to produce a battery having both terminals on one face.Preferably the wrapper pieces are laminates of metal and electricallyconductive plastic, with the plastic being in contact with the endelectrodes and an extension of the metal in the laminate serving as theterminal which is wrapped around the edge of the battery. The wrappedaround extension, which must be electrically insulated from the wrapperpiece over which it is overlaid, may be secured to the other wrapperpiece by nonconductive adhesives or heat seals.

BACKGROUND OF THE INVENTION Flat, multicell batteries have beenconstructed for many years by stacking individual cells on top of oneanother and connecting them together in series. These batteries haveterminals of opposite polarity which are physically located at theopposite sides of the battery. There is good reason to locate bothterminals on a common side of the battery since it is generally easierto connect the battery to its appliance if the appliance connectionterminals can be located in a common plane. This is especially truewhere a flat cell battery operates a flat pack appliance, or itotherwise located with one side adjacent to appliance parts, so that oneside of the flat cell battery is in such a position as to make contactdifiicult or otherwise undesirable.

Various ways have been devised to bring one terminal around the exteriorof the flat cell batteries so as to have both terminals on one side, butsuch methods have been generally unsatisfactory either from point ofcost of ma terials, cost of labor, added thickness to the battery, orcontact resistance.

In all fiat cell batteries a moisture barrier is essential to extendshelf life. In some constructions this is accomplished by a polymericcoating such as a wax dip or by a plastic sleeve sealed at the ends andhaving terminal protrusions.

In another previously filed application, Ser. No. 99,985, it has beenproposed to build a battery having a wrapper which consists of twopieces sealed around their perimeters. Each wrapper piece comprises alaminate of metal and electrically conductive plastic, the conductiveplastic in each of the laminates being in contact with an end electrodewithin the battery. The wrapper pieces are closed around the perimetersof the electrodes to produce a liquid impervious sealed battery. Thewrapper pieces provide superior moisture retention and thereforeincrease the shelf life of the battery. Another of their advantages isthe fact that they can be placed directly in contact with the endelectrodes without producing any undesired electrochemical reactions.Still another and an important advantage of the laminated Wrapper piecesis the relative conductivities of the conductive plastics and themetals.

Conductive plastics tend to be good conductors of electricity in theirtransverse direction, i.e., across their thicknesses, but they arepoorer conductors of electrical current in their longitudinal direction.The metal, on the other hand, is a good conductor in all directions andis therefore well suited to collect current all along its interface withthe adjacent conductive plastic and to conduct that currentlongitudinally to a terminal.

SUMMARY OF THE INVENTION This invention consists of an improvement inflat cell batteries which improvement requires the use of two wrapperpieces. Each wrapper piece is in contact with an end electrode of thebattery so as to serve as a current collector for that electrode, as aterminal for the battery, and as a moisture barrier. The wrapper piecesare sealed around the perimeter of the electrodes by moistureimpervious, electrically nonconductive sealing means. An extension ofone of the Wrapper pieces is wrapped around the edge of the battery andoverlays the other wrapper piece. The wrapped around extension, whichmust be electrically insulated from the wrapper piece over which it isoverlaid, may be secured to the other wrapper piece by nonconductivesealing means such as nonconductive adhesives, heat seals, and variouspressure sensitive coated materials.

It is preferred to use the laminates of conductive plastic and metal ofSer. No. 99,985 as the wrappers used in this invention, in which casethis invention represents an improvement over the one of Ser. No.99,985. In that case the plastic in each laminated wrapper piece is incontact with one of the end electrodes. Also in that case it ispreferred to extend the metal in one of the wrapper pieces beyond theedge of the laminate of which it is a component, wrap that extensionaround the edge of the battery, and overlay that extension on top of theother wrapper piece.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a pictorial view of a flatmulticell battery having both terminals on one face.

FIG. 2 illustrates a cross-section of the battery shown in FIG. 1 takenalong the line AA of FIG. 1. The thickness of the battery is showngreatly magnified for purposes of illustration. FIG. 2 shows the metalof a metal-conductive plastic laminated wrapper piece being wrappedaround the edge of the battery and secured to the wrapper piece overwhich it is overlaid by an electrically nonconductive adhesive.

FIG. 3, which shows an alternative to the construction illustrated inFIG. 2, shows both the metal and the plastic of a metal-conductiveplastic laminated wrapper piece being wrapped around the battery andsecured to the other wrapper piece by an electrically nonconductiveadhesive.

FIG. 4 differs from FIG. 2 by having the metal extension secured to theother wrapper piece by an electrically nonconductive heat seal.

FIG. 5 differs from FIG. 2 by having a nonconductive paper interposedbetween the metal extension and the wrapper piece over which it isoverlaid and by having the battery enclosed within a nonconductiveplastic film.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a flat multicellbattery 5 in a pictorial view. FIG. 2 shows a portion of the multicellbattery 5 in magnified cross-section. As FIG. 2 shows, the batterycomprises the combination of at least two cells 10, each such cellcomprising a positive electrode 20, a negative electrode 30, and anelectrolyte impregnated separator 40 between the positive electrode 20and the negative electrode 30. Between each adjacent pair of cells is animpervious intercell connector 50. Portions of the separator extendingbeyond the edges of the electrodes are impregnated with electricallynonconductive adhesive 100 to provide a liquid impervious seal betweenand around the perimeters of the intercell connectors. A single cellbattery similar to the one shown in FIG. 2 would contain only one cell10 and no intercell connectors.

The multicell battery also requires a liquid impervious wrapper to besealed around the outermost cells. As it pertains to the presentinvention, that wrapper consists of two pieces, each of which preferablycomprises a laminate of metal and electrically conductive plastic. FIG.2 illustrates these two preferred wrapper pieces, one piece 60-80comprising a laminate of metal 60 and electrically conductive plastic 80in which the plastic 80 is in contact with the positive electrode in oneof the end cells and the other piece 70-90 comprising a laminate ofmetal 70 and electrically conductive plastic 90 in which the plastic 90is in contact with the negative electrode in the other end cell. Oneadvantage of the laminated wrapper pieces is that conductive plasticsmay be placed in direct contact with the electrodes so that theconductive plastics function as current conductors. It will be notedthat the conductive plastic will not produce an undesiredelectrochemical reaction when placed in direct contact with the positiveelectrode, and so it is unnecessary to interpose between them a depositof conductive adhesive to prevent such reactions.

Another advantage of the laminated wrapper pieces is the relativeconductivities of the conductive plastics and the metals. Conductiveplastics tend to be good conductors of electricity in their transversedirection, that is, across their thicknesses, but they are poorerconductors of electrical current in their longitudinal direction. Themetal, on the other hand, is a good conductor in all directions and istherefore well suited to collect current all along its interface withthe adjacent conductive plastic and to conduct that currentlongitudinally to a terminal.

Still another advantage of the metal-conductive plastic laminates istheir superior resistance of the penetration of moisture. One of thegreatest limitations to long shelf life in a battery is the problem ofhaving moisture from the electrolyte slowly escape from the batterybefore the battery is placed into service. One of the ways in which thismoisture can escape is by penetration through the wrapper. The laminatedwrapper pieces reduce the opportunities for such moisture penetration byproviding a double moisture barrier around the battery. The innerplastic layers prevent the passage of moisture in the form of liquid,although the tiny pores which are occasionally found in plastics mayallow the slow passage of vapors; but the other metal layers, which aresubstantially free of these pores, act as vapor barriers. A furtheradvantage of the metal in the laminated wrapper is the increased area onwhich to make terminal contacts. Additionally, thin [foils of metalallow more flexible constructions.

The metal layers 60 and 70 may be thin sheets or foils; alternativelythey might be thin spray or vacuum deposits or electrodeposits, in whichcase they may be deposited on a substrate (e.g., the electricallyconductive plastic or a nonconductive material) if they are notself-supporting. Preferably, however, the metals 60 and 70 are thinfoils of steel which may have a tin coating to decrease contactresistance. Such steel rfoils are readily available, relativelyinexpensive, good electrical conductors, and are generally free ofpores. They may also be laminated to some conductive plastics by theapplication of heat and pressure, without requiring any intermediaryadhesives between them. The steel foils can be purchased in rolls ofgreat 4 length and are thus well suited for use in high speed,continuously operating production machinery. Foils of aluminum, lead,zinc and a wide variety of other metals may also be used.

The conductive plastics may be produced by casting, extrusion,calendering or other suitable techniques. The conductive plastics may bemade, for example, from materials such as polymers loaded withelectrically conductive particles and containing various stabilizersand/or plasticizers, or from conductive polymers. The conductiveparticles may be carbonaceous materials such as graphite or acetyleneblack, or metallic particles may also be used. The conductive plastic,whether loaded or unloaded, must be made from a composition which iscompatible with the other components of the battery. For batteries usingLeClanche and moderately concentrated alkaline electrolytes, theconductive plastic may be made for example, from materials such aspolyacrylates, polyvinyl halides, polyacrylonitriles, copolymers ofvinyl chloride and vinylidene chloride, polychloroprene, andbutadiene-styrene or butadiene-acrylonitrile resins. For batteries usingstrongly alkaline electrolyte, polyvinylchloride and polyolefins such aspolyethylene and polyisobutylene may be used in the preparation of theconductive plastic. For batteries using acid electrolytes such assulfuric acid, polyvinyl halides, copolymers of vinyl chloride, andvinylidene chloride may be used.

The laminated wrapper pieces may, of course, also be used with singlecell batteries. In such cases there is only one cell 10, there are nointercell connectors 50, and an electrically nonconductive sealing meanssuch as sealer 100 shown in FIG. 2 must be used between the laminatedwrapper pieces. Except for these changes, the remarks made above inregard to multicell batteries are applicable also to single cellbatteries.

Batteries having wrappers comprising the two laminated pieces describedabove are the subject matter claimed in Ser. No. 99,985.

FIG. 2 illustrates how the laminated wrapper pieces of Ser. No. 99,985may be used to provide the wrapped around terminal which is the featureof this invention. As shown in FIG. 2, extension 70E of the lowerwrapper piece extends beyond the edge of the laminate 70-90, themetallic extension 70E being wrapped around the edge of the battery 5 tooverlay the other wrapper piece -80. The wrapped around extension Eapplies substantially no crimping forces against the wrapper piece 60-80over which it is overlaid. The metallic extension 70E is elec tricallyinsulated from but secured to the upper wrapper piece 60-80 by anelectrically nonconductive adhesive 100E. The adhesive 100E preferablycoats the inside surface of the metallic extension 70E to preventelectrical conductivity between that extension and the edges of any ofthe intercell connector 50. The preferred wrapped around terminal couldbe sealed to the bottom rather than to the top side of the battery byextending the metal 60 of the upper laminate piece 60-80 around the edgeof the battery and adhering it to the bottom laminate piece 70-90. Theextension of the metal in one of the laminates to serve as the wrappedaround terminal provides a member having very good electricalconductivity.

FIG. 3 shows an alternative construction in which the entire laminate70-90 is extended around the edge of the battery so that extensions 70Eand E are used to provide the wrapped around terminal. FIG. 3 alsodiffers from FIG. 2 by having the separators 40 extend only slightlybeyond the edges of the electrodes 20 and 30 rather than to the edges ofthe intercell connectors and by using deposits of electricallynonconductive adhesives around the perimeters of the intercellconnectors which are not impregnated into the separators.

FIG. 4 shows a construction which differs from the one appearing in FIG.2 by having an electrically nonconductive, heat scalable mamber 102rather than a nonconductive adhesive interposed between metallicextension 70B and the upper wrapper piece 60-80. The member 102 may beheat sealed to both the metallic extension 70E and the upper wrapperpiece 60-80 so as to secure the metallic extension and the upper wrapperpiece together. The nonconductive, heat sealable members may be madefrom such materials as polystyrene, polyvinyl chloride, acrylonitrylbutadiene styrene, phenolics, vinylidine chloride, cellophane, celluloseacetate, polyurethane films, natural and artificial rubbers, and others.

A construction similar to the one shown in FIG. 4 may also be built bycementing nonconductive member 102 to both the metallic extension 70Eand the upper wrapper piece 60-80 with an adhesive.

FIG. 5 shows a construction in which the metallic extension 70E of thelower laminated wrapper piece 70-90 is wrapped around the edge of thebattery to overlay the other wrapper piece 60-80. An electricallynonconductive, nonsecuring (i.e., nonadhesive, non-heat sealing, etc.)member 104 is interposed between the extension 70E and the wrapper piece60-80. Such members 104 may be made from a wide variety of materialsincluding papers, felts, and fabrics composed of natural or syntheticfibers as well as continuous films of cellophane, polyolefins, celluloseacetate, and many others. Also shown in FIG. 5 is an enclosure member106 which may be placed around the battery for such purposes aselectrical insulation, improved moisture retention and others. Enclosuremember 106 may comprise a single component as shown in FIG. 5 or it mayinclude two or more components which cooperate to produce the desiredresults. Enclosure member 106 may be used to hold the metallic extension70E and the nonsecuring member 104 closely against the upper wrapperpiece 60-80.

While the preferred constructions have been shown in the drawings anddescribed above, other embodiments are also possible. As one example,the metallic foils 60 and 70 illustrated in the drawings may be replacedwith metal flame sprays or with films impregnated with metallic or otherconductive particles and applied by casting, doctor blading, or othertechniques. As another example, the battery could have a pair of wrapperpieces each of which consisted of only electrically conductive plastic,analogous to components 80 and 90 shown in FIGS. 2 through 5; such aconstruction, while functional, does not provide the same high degree ofmoisture retention in the battery as do the metal-plastic laminates and,in addition, the plastic is a poorer longitudinal conductor. As anotherexample, the battery could have a pair of wrapper pieces each of whichconsisted of only metal, the surface of the metal which is in contactwith the end electrodes being electrochemically inert with respect tothe other battery components; such metals, which might be of homogeneouscomposition or which might comprise one metal clad or coated withanother, may be more expensive compared with the preferred plastic-metallaminates. Still another alternative is to use a pair of wrapper pieceseach of which consisted of metal coated on the inside with anelectrically conductive adhesive which would prevent undesiredelectrochemical reactions between the metallic wrapper pieces and othercomponents of the battery.

The composition of each of several of the other members in the batterymay take alternative forms, and the composition of those members willnow be discussed.

The positive electrodes 20 may comprise particles of electrochemicallypositive active material contained in and dispersed throughout a bindermatrix. The positive active material conventionally is divided into tinyparticles so as to increase the ratio of total surface area to weight inthe active material and thereby increase the rate at which theelecrochemical reactions can occur by increasing the surface areas wherethey occur. The binder increases the electronic conductivity and thestructural integrity within the electrodes. Since electrolyte must haveaccess to the surface of the active material particles, the electrodemust be made sufficiently porous so that the electrolyte may diffusethroughout the electrode rapidly and thoroughly. Preferably the pores inthe electrode are produced by the evaporation of liquid during theconstruction of the electrode; the evaporating liquid may be part of adispersion binder system in which the solid binder contained in thefinally constructed electrode comprises tiny particles of bindermaterial dispersed throughout and not dissolved in the liquid while theelectrode is being constructed, or the evaporating liquid may be part ofa solution binder system in which the solid binder contained in thefinally constructed electrode is dissolved in the liquid which is laterevaporated. The porosity of the positive electrodes may be increased asthe discharge rate desired in the battery is increased. Electrodes mayalso be constructed using combinations of the dispersion and solutionsystems. Alternatively, the pores might be produced by the dissolving ofa solid which was present during construction of the electrode or bypassing gases through or generating gases within the electrodes atcontrolled rates during electrode construction. The positive electrodes20 may, and preferably will, also contain amounts of good electricalconductor such as carbon or graphite to improve the electricalconductivity between the active material particles, the positive activematerial particles themselves generally being relatively poor conductorsof electricity. The conductivity of the active material particlestogether with the conductivity of the binder itself will influence theamounts of conductors added to the electrode. The electrodes 20 may alsocontain if desired small amounts of additional ingredients used for suchpurposes as maintaining uniform dispersion of active material particlesduring electrode construction, aiding the diffusion of electrolytethrough the pores of the finally constructed electrodes, controllingviscosity during processing, controlling surface tension, controllingpot life, or for other reasons.

The negative electrodes 30 may comprise spray or vapor deposits ofmetals or may comprise tiny particles of metals contained in anddispersed throughout a binder matrix. If the negative electrodes utilizea binder matrix, in general the same considerations regarding thatmatrix apply to the negative electrodes as do for the positiveelectrodes except that no electrical conductor may be needed to achievedesired electrical conductivity between the active material particlessince the negative active materials are generally better conductors thanare the positive materials. When the negative electrodes utilize abinder matrix, the binder system need not be the same as the one used inthe positive electrodes, and even if it is the proportions of binder,active material particles, and other ingredients in the negativeelectrodes may have a diiferent optimum than the proportions ofanalogous ingredients in the positive electrode. The initial porosity ofthe negative electrodes may sometimes be less than that of the positiveelectrodes, since the negative electrode discharge reaction products aresometimes dissolved in the battery electrolyte. The porosity of thenegative electrodes may be increased as the discharge rate desired inthe battery is increased. The negative electrodes 30 may also comprisethin sheets or foils or electrodeposits of electrochemically negativematerial.

Between the two electrodes in each cell is an electrolyte impregnatedseparator 40, the theoretical requirements of which are that it containelectrolyte as well as physically separate and prevent contact betweenthe electrodes. A deposit of gelled electrolyte could by itself serveboth functions if of proper thickness and/or consistency. Thealternative construction uses a deposit of gelled or fluid electrolytewith a separator which is distinct from and in addition to theelectrolyte, the separator providing added insurance against directcontact between the electrodes and acting as an absorbent material intowhich the electrolyte may be impregnated. Both alternative constructionsmay, however, be viewed as being forms of electrolyte impregnatedseparators. Where the separator is distinct from and in addition to theelectrolyte, the separator may be made from a wide variety of materialsincluding the fibrous and cellulosic materials which are conventional inbattery construction as well as from woven or non-woven fibrousmaterials such as polyester, nylon, polypropylene, polyethylene andglass.

Between each consecutive pair of cells is an impervious intercellconnector 50 which may take several diiferent embodiments. Regardless ofthe specific embodiment, the impervious intercell connector 50 must meetthree essential requirements: it must be impervious to the electrolyteof the battery so that one cell may be sealed off from the next; it mustprovide some means by which electrical current may be conducted betweenthe positive electrode in one cell and the negative electrode in thenext cell; and it must not create any undesired electrochemicalreactions with the electrodes or other components of the battery.

The particular embodiment of the impervious intercell connector shown inFIGS. 25 may be a sheet or film of electrically conductive plastic.Alternative embodiments of the impervious intercell connector may beachieved with metal foils, conductive adhesives or combinations of them,since with the use of metal foils it may be necessary or desirable tointerpose a layer of conductive adhesive or other conductive polymerbetween the foil and the positive electrode 20 to prevent the foil fromengaging in an undesired electrochemical reaction with the positiveelectrode or the electrolyte. The impervious intercell connector 50 mayalso be a combination of an electrically nonconductive member such asplastic, with one or more members of electrically conductive materialextending around the edge of or through the nonconductive member toconduct electrical current between the positive electrode in one celland the negative electrode in the next consecutive cell.

Liquid impervious seals must be provided between each intercellconnector 50 to prevent the escape of moisture from the interior of thebattery. Adhesive means for achieving this sealing are shown in FIGS.2-5 as items 100. If the adhesive is made from an electricallynonconductive material, members 100 may serve an additional purpose,that of preventing undesired electrical connections between two or moreelectrically conductive members of the battery. Where the edges of theintercell connectors are themselves electrically nonconductive, as theymay be in the case of intercell connectors comprising a combination ofelectrically nonconductive plastic with one or more conductive membersextending around the edge of or through the nonconductive plastic, thenonconductive perimeters of the intercell connectors may serve as thesealing means by being sealed with the application of heat and/orpressure or by some other technique.

While it is preferred to employ the LeClanche electrochemical system(comprising manganese dioxide positive active material, zinc negativeactive material, and an electrolyte comprising ammonium chloride and/orzinc chloride), the battery 5 of this invention may employ a widevariety of electrochemical systems including both primary and secondarysystems. Among the positive electrode materials are such commonly usedinorganic metal oxides as manganese dioxide, lead dioxide, nickeloxyhydroxide, mercuric oxide, and silver oxide, inorganic metal halidessuch as silver chloride and lead chloride, and organic materials capableof being reduced such as dinitrobenzene and azodicarbonamide compounds.Among the negative electrode materials are such commonly used metals aszinc, aluminum, magnesium, lead, cadmium, and iron. This invention maywith appropriate electrodes employ the electrolytes commonly used in theLeClanche system (ammonium chloride and/or zinc chloride), variousalkaline electrolytes such as the hydroxides of potassium, sodium,and/or lithium, acidic electrolytes such as sulfuric or phosphoric acid,nonaqueous electrolytes, the electrolytes of course being chosen to becompatible with the positive and negative electrodes.

Among the wide variety of electrochemical systems which may be used inthe battery 5 are those in which the positive electrodes comprisemanganese dioxide, the negative electrodes comprise metals such as zinc,aluminum, or magnesium, the electrolyte substantially comprises anacidic solution of inorganic salts. Another commonly known system usefulin the battery 5 is the alkaline manganese system in which the positiveelectrode comprise manganese dioxide, the negative electrodes comprisezinc, and the electrolyte substantially comprises a solution ofpotassium hydroxide. Other aqueous electrolyte systems including thoseof nickel-zinc, mercury-zinc, mercury-cadmium, and nickel-cadmium mayalso be used. Systems employing organic positive electrodes and acidicelectrolytes may also be used, including rechargeable systems usingazodicarbonamide compound electrodes and LeClanche electrolyte.

We claim:

1. An improvement in a flat cell battery comprising the combination of(a) at least one fiat cell and (b) a wrapper consisting of twoelectrically conductive pieces, each of which is in contact with an endelectrode of the battery so as to serve as a terminal for the battery,the wrapper pieces being sealed around the perimeters of the electrodesby moisture impervious, electrically nonconductive sealing means,

wherein the improvement comprises an extension of one of the wrapperpieces which extension (i) is wrapped around the edge of the battery andis overlaid on the other wrapper piece so that both wrapper pieces areexposed and provide electrical terminals on the same fiat face of thebattery,

(ii) is electrically insulated from the wrapper piece over which it isoverlaid by electrical insulating means,

(iii) is sealed by moisture impervious sealing means with the wrapperpiece over which it is overlaid so that moisture cannot escape betweenthe two wrapper pieces, and

(iv) applies substantially no crimping forces against the wrapper pieceover which it is overlaid.

2. The improvement of claim 1 wherein the wrapper pieces compriselaminates of metal and electrically conductive plastic, the plastic ineach piece being in contact with one of the end electrodes of thebattery.

3. The improvement of claim 2 wherein the metal in one of the wrapperpieces is extended beyond the edge of the laminate of which it is acomponent and wherein the metal extension is wrapped around the edge ofthe battery and extended to overlay the other wrapper piece.

4. The improvement of claim 1 in which the extension is moistureimperviously sealed to and electrically insultated from the wrapperpiece over which it is overlaid by an electrically nonconductiveadhesive.

5. The improvement of claim 1 in which the extension is moistureimperviously sealed to and electrically insulated from the wrapper pieceover which it is overlaid by an electrically nonconductive heat seal.

6. The improvement of claim 3 in which the extension is moistureimperviously sealed to and electrically insulated from the wrapper pieceover which it is overlaid by an electrically nonconductive adhesive.

7. The improvement of claim 3 in which the extension is moistureimperviously sealed to and electrically insulated from the wrapper pieceover which it is overlaid by an electrically nonconductive heat seal.

(References on following page) 10 References Cited 3,379,574 4/1968Grulke et a1. 136-112 X Balaguer -r 7/1958 lacquier 136-411 ANTHONYSKAPARS, Primary Examiner 1/1959 Solhs 136-111 5 5/1956 Nowotny 136-111US. Cl. X.R.3

3/1959 Nowotny 136-111 136-132, 135 i 3/1963 Brown 136-111

